Recently, there has been an increasing number of surgeons using clips, instead of conventional suture ties, to occlude blood vessels and the like. In a typical surgical procedure, many veins, arteries and blood vessels must be tied off, prior to the severing thereof, in order to reach the surgical site. This is an often difficult and time-consuming procedure, since many vessels are located in areas where there is very little room to work. It is important that the occlusion be positive to minimize bleeding, and due to the fact that once severed, the blood-carrying vessels tend to retract into the surrounding tissue and are difficult to retrieve. As used herein and the in the claims, the term "vessel" and "vessels" should be considered in the broad sense to be inclusive of veins, arteries and the like, to which ligator clips are normally applied.
Prior art workers have devised numerous types of surgical ligating instruments designed to clamp blood vessels. There are, for example, reusable, permanent-type ligating instruments, and instruments which are intended to be disposed of after use. There are also ligating instruments wherein each clip is individually loaded in the instrument. Other ligating instruments utilize pre-sterilized cartridges holding a multiplicity of clips. Yet another general class of ligating instruments is provided with a magazine within the instrument, containing a plurality of clips.
The teachings of the present invention are applicable to ligating instruments of the general type having a pair of clamping jaws and a pusher by which a clip is located in position between the jaws, ready to be clamped about a blood vessel or the like. While not intended to be so limited, for purposes of an exemplary showing, the present invention will be described in its application to a disposable surgical ligator of the type taught in the above mentioned co-pending applications Ser. No. 435,380 and Ser. No. 546,928. The teachings of these co-pending applications are incorporated herein by reference.
Briefly, the disposable surgical ligating instrument of co-pending application Ser. No. 435,380 comprises a first handle terminating at its forward end in a first jaw. A second jaw is pivotally mounted to the first handle so as to cooperate with the first jaw. A second handle is pivotally mounted at its forward end to the first handle and is provided with a lug to actuate the second jaw. The handles are shiftable between open and closed positions, and shift the first and second jaws between opened and closed, clip-clamping positions. A magazine in the form of a clip tube, containing a plurality of clips lying one behind the other in the same plane, is mounted in the first handle. A feeder shoe is mounted in the clip tube and constantly urges the row of clips forwardly therein through the agency of a constant-force coil spring. Adjacent and along the clip tube, a pusher is mounted in the first handle in a pusher track which is continued to the forward ends of the jaws. The pusher is shiftable by the first and second handles between a retracted position, when the handles are closed, and an extended position, to locate a clip in the pusher track between the forward ends of the jaws, when the handles are open. The first handle provides a ramp structure leading to the pusher track at the forward end of the clip tube. The ramp structure is covered by the pusher when in its extended position. The ramp is exposed by the pusher when in its retracted position, enabling the forwardmost clip of the row to be transferred from the clip tube, via the ramp, to the pusher track in front of the pusher, due to the forward urging of the clips by the feeder shoe.
When the first and second handles are shifted from their closed to their open positions, the first and second jaws will also shift from their closed to their open positions and the pusher will locate a clip in the pusher track at a position between the forward ends of the jaws, ready for clamping. When the first and second handles are squeezed toward each other to their closed positions, the pusher will shift to its retracted position enabling the next forwardmost clip of the row to be ramped or transferred into the pusher track. Immediately thereafter, the first and second jaws will close, clamping the clip therebetween about the vessel to be occluded. This sequence of events is repeated with each opening and closing of the handles, the clip feeding system requiring no force on the part of the surgeon to accomplish its purpose.
Copending application Ser. No. 546,928 teaches a clip stop in the form of a simple resilient wire member which remains between the jaws at all times. The clip stop prevents each clip from being shoved rearwardly in the pusher track by a vessel during the application of the clip thereto and the clamping of the clip thereabout. In addition, the clip stop assures that the clip is separated from the pusher during the initial part of the clip-applying and clamping operation, when the pusher begins to retract from between the jaws.
It has been found that in the absence of a positive means to shift the forwardmost clip from the tube-like cartridge to the pusher track, misfeeding and/or double feeding can occur. In addition, a non-positive system such as the above noted ramp means requires very precise tolerances. The present invention is based upon the discovery that if a staging area is provided at the forward end of the tube-like magazine and if a jaw-actuated plunger is used to positively shift the forwardmost clip from the staging area to the pusher track, the above noted problems will be eliminated. The positive feed system of the present invention is capable of shifting clips of different shapes. The shape of the plunger may be changed to match the shape of the clip, if required. The positive feed system of the present invention can also be used to feed all sizes of ligator clips, so long as the overall surgical ligating instrument is properly scaled for the size fo clip being used. The feed system is capable of shifting both metallic and non-metallic ligator clips.